The invention relates generally to providing a supplementary service, such as a short message service, in a mobile communications system.
Mobile communications systems, such as cellular or personal communications services (PCS) systems, are made up of a plurality of cells. Each cell provides a radio communications center in which a mobile unit establishes a call with another mobile unit or a wireline unit connected to a public switched telephone network (PSTN). Each cell includes a radio base station, with each base station connected to a mobile switching center that controls processing of calls between or among mobile units or mobile units and PSTN units.
Several protocols exist for circuit-switched wireless communications, including the advanced mobile phone system (AMPS) standard, the TIA/EIA-136 time-division multiple access (TDMA) protocol from the Telecommunications Industry Association (TIA), the Global System for Mobile (GSM) TDMA protocol from the European Telecommunications Standards Institute (ETSI), and the IS-95, IS-95A, and IS-95B code-division multiple access (CDMA) standards from the TIA.
Traditional speech-oriented wireless systems utilize circuit-switched connection paths in which a channel (or a portion of channel such as a time slot) is occupied for the duration of the connection between a mobile unit and the mobile switching center. Such a connection is optimum for communications that are relatively continuous, such as speech. However, data networks such as local area networks (LANs), wide area networks (WANs), and the Internet use packet-based connections, in which communication between nodes on a communications link is performed with data packets. Each node occupies the communications link only for as long as the node needs to send or receive data packets. Such communications are bursty in nature, with packets sent in bursts followed by periods of inactivity.
One wireless communications protocol for providing more efficient connections between a mobile unit and a packet-based data network such as an Internet Protocol (IP) network includes the General Packet Radio Service (GPRS) protocol from ETSI, with versions complementing existing GSM systems and TIA/EIA-136 systems. In a GPRS communications system, various entities are present. A serving GPRS support node (SGSN) controls communications between mobile units and a packet-based data network. The SGSN is typically connected to a gateway GPRS support node (GGSN), which provides the interface to the packet-switched data network. The SGSN is connected to base station systems (BSS) over respective Gb interfaces, which provide for the exchange of control signaling and user data. Versions of GPRS also include Enhanced GPRS (EGPRS) and EGPRS COMPACT. Another wireless communications protocol, used for CDMA systems and that provides efficient packet-based communications, is the IS-2000 standard established by the TIA.
In addition to basic voice call services, mobile communication systems also provide various supplementary services to users. Depending on the service provider, service fees may be charged for services that users subscribe to. Thus, while users have the flexibility in selecting services that they desire, service providers are able to extract revenue from supplementary services. One type of supplementary service is a short message service (SMS). SMS can be used to carry paging data to enable a caller to page a mobile telephone (similar to sending pages to pagers). Short message service is also used to deliver voice mail waiting indicators as well as to deliver data such as sports scores, stock tickers, and other short messages.
Although SMS enables convenient communication with remote users, some mobile communications systems have not defined a mechanism to support some forms of short message services (e.g., prepaid short message services). A prepaid short message service is a service that a user has prepaid and that can be used as long as the associated prepaid account has a sufficient balance. Other types of prepaid supplementary services also exist.
A need thus continues to exist for mechanisms to enable some forms of supplementary services, such as prepaid short message services.
In general, according to one embodiment, a system for use in a mobile communications system comprises an interface to receive a predetermined field from a home location register to indicate whether a user has subscribed to a prepaid supplementary service. A controller is adapted to provide access to packet-based network and to enable the prepaid supplementary service if the predetermined field has a first state.
Some embodiments of the invention may have one or more of the following advantages. More services can be provided to users in some mobile communications systems. With a greater variety of services available to users, user convenience is enhanced. Also, service providers benefit by being able to collect revenue based on usage of such supplementary services.
Other features and advantages will become apparent from the following description, from the drawings, and from the claims.